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Pollution Solution

By Bill Dawson

An experimental wetland on the Trinity River aims to both clean up water and help wildlife.

Fort Worth’s tap water probably is not the first thing that comes to mind when visitors to Richland Creek Wildlife Management Area gaze across an attractive new wetland studded with marsh grasses and wading birds.

Even so, filtering pollutants from Trinity River water so it can be provided to Fort Worth, Arlington and other cities in the growing Metroplex area for purification was the central motive behind this wetland-creation project about 80 miles southeast of Dallas. Through natural processes, sediments will settle out of river water pumped to the new wetlands, where aquatic plants and other organisms will remove troublesome nutrients such as nitrogen and phosphorus.

The new wetland has been created though a partnership between the Texas Parks and Wildlife Department and Tarrant Regional Water District, whose officials hope an array of benefits will flow from the possibly precedent-setting collaboration. They include providing a relatively cheap new water source; delaying the need to consider building a new habitat-destroying reservoir; and creating a dependable supply of water for wetlands at TPWD’s wildlife management area.

Securing that supply was one key consideration for department officials when the water district proposed the project. The nearly 14,000-acre Richland Creek WMA was established in 1987 as required mitigation for the district’s 45,000-acre Richland Chambers Reservoir, which claimed a large chunk of the state’s diminishing bottomland hardwood habitat.

Until now, replacement wetlands created at Richland Creek — most notably, a 580-acre project of TPWD and Ducks Unlimited, Inc. — have had no guaranteed water supply, relying instead on nature’s vagaries in the Trinity floodplain.

Larry McKinney, TPWD’s senior director for aquatic resources, says he was intrigued but “a little skeptical” when the water district approached department officials with the idea of building water-filtering wetlands. After a small pilot project during the 1990s, plus detailed study of the potential pluses and minuses, he concluded it held great promise.

“It’s as good an example as I’ve seen of a project that meets the water demands of a growing population with a positive impact on wildlife,” McKinney says.

The district’s Richland Chambers Reservoir now collects water only from tributaries that feed the Trinity. Nearby, the river carries greater concentrations of contaminants from upstream sources, including treated wastewater discharges from the Dallas-Fort Worth area, as well as urban and agricultural runoff.

Before proceeding with their full plan to filter river water in the wildlife management area, district officials wanted assurance that it was likely to produce water as clean or cleaner than what they take from the tributaries, Richland and Chambers creeks.

The five-acre pilot project’s wetlands performed so well — yielding water lower in sediment and nutrients than those streams — that another 250 acres of wetlands were constructed during the last couple of years for further tests, says Darrel Andrews, a water quality manager for the district. This phase was dedicated in May. If it produces good results, creation of another 250 acres of wetlands is scheduled to start in 2005. Once that phase is operating efficiently, water from the wildlife management area finally will start flowing into the reservoir in 2007.

Ultimately, officials intend to create a complex of about 2,000 acres of wetlands at Richland Creek, to be completed around 2020. The water district will pay the estimated $22 million in capital costs. The finished project will provide enough additional water to the reservoir for an estimated 300,000 people. As it is phased in, officials say they will monitor for any worrisome buildup of toxic materials from the Trinity in sediments being deposited in the wildlife management area. TPWD officials, however, expect enhancement of the wildlife management area, particularly for its two most popular public uses: waterfowl hunting in the fall and bird watching in the spring. Birders also converge there in July to observe about 300 wood storks on their annual visit.

“A key component of this project was to retain all public-use activities on the surface,” says Jeffrey Gunnels, a TPWD wildlife biologist who manages Richland Creek.

Before agreeing to the proposal, department officials satisfied themselves that increasing water use in the Dallas-Fort Worth area — producing growing discharges into the Trinity — would help offset any negative environmental impact of taking large volumes of water from the river for the new wetlands.

“We wanted to make sure there was enough water in the river to keep it healthy,” McKinney says.

He acknowledges that controversy over the project still could arise in a severe drought if downstream users such as the City of Houston demand the total amount of Trinity water allowed in their permits.

Still, he believes the Richland Creek project is an especially timely model as Texas increasingly grapples with how to balance the water needs of cities and the environment. “This is one of the tools that can work,” he says. “This is one example of how we can meet everyone’s needs.”